Railway vehicle brake equipment



Oct. 19, 1937. J. w. LOGAN; JR

RAILWAY VEHICLE BRAKELEQUIPMENT 5 Sheets-Sheet '1 Filed Nov. 23, 1935 JOHN w. LOGAN, JR. %a/

A'ITORNEY Oct. 19, 1937. h J w LOGAN. JR 2,096,433

RAILWAY VEHICLE BRAKE EQUIPMENT Filed Nov. 25, 1955 5 Sheets-Sheet 2 as 45 v 46 p\\ TIIIIII IJiIIWII/A 6 33 4 ATTORNEY I23 33 124 I34 I25 I35 I26 I36 I27 0 I37 5 55 X-CLOSED.

58 o QPEN' lNVEN TOR JOHN w. LOGAN,JR.

Oct. 19, 1937. J. W. LOGAN, JR 6 3 RAILWAY vEaIcL'E BRAKE EQUIPMENT 7 Filed Nov. 2:5, 19:55 Y s Sheets-Sheet s v 479" 231 K 477 7a 480' u 235 Fig.6

505 50 mvzm-oa JOHN W LOGAN JR.

A'ITORNEY v I N Posmon Oct. '19, 1937. J, w LOGAN. JR I 2,096,433

RAILWAY VEHICLE BRAKE EQUIPMENT Filed Nov. 23 1935 5 Sheets-Sheet 5 224 E w aeoa 599 I 62 593 INVENTOR 592 57| JOHN.\ LOGAN JR ATTORNEY Patented Oct. 19, 1937 UNITED STATES PATENT orrlca RAILWAY VEHICLE BRAKE EQUIPMENT John W. Logan, In, Forest Hills, Pa., assignor to The Westinghouse Air Brake Company, Wilmerding, Pa., a corporation of Pennsylvania Application November 23, 1935, Serial No. 51,218

58 Claims.

I the same order as now exist in the case of trains traveling at a lower speed, it has become increasingly important to guard against sliding of the wheels of the train.

As is well understood by those skilled in the art, sliding of the wheels of a train upon application of the brakes is due to the fact that the retarding force acting to impede rotation of the wheels overcomes the adhesion between the wheels and the rails. Adhesion between a wheel and the rail along which it rolls may be expressed in terms of a coeflicient of adhesion which is the ratio of the maximum tangential retarding force that can be effective on a wheel without causing it to slide, relative to the weight supported by and pressing the wheel to the rail, the coefficient usually being expressed as per-cent of the weight pressing the wheel to the rail.

It is well known that when a wheel is sliding along the rails thefrictionalcontact between the wheel and the rail produces a braking effect on the wheel which is considerably less than the braking effect produced when the wheel is permitted to continue rolling along the rail while subject to a force of retardation just insumcient to cause the wheel to slide. It follows therefore from the fact that the maximum braking eifect or rate of retardation of a wheel is that which results from the imposition of a maximum retarding force which will not cause the wheels to slide, that the degree of braking effect produced on a wheel will be in proportion to the ratio which the actual retarding force imposed on a wheel bears to the maximum retarding force capable of being imposed on a wheel without causing it to slide.

Since the maximum retarding force capable of being imposed on a wheel without causing it to slide represents the maximum degree in terms of retarding force to which the adhesion between the wheel and the rail may be utilized, the percentage or degree of the actual retarding force acting on a wheel relative to the maximum retarding force which may be imposed on a wheel without causing it to slide is hereinafter referred to as the degree of adhesion utilization.

It follows therefore, that if the degree of adhesion utilization is maintained less than the maximum degree to which the adhesion may be utilized, that a wheel will not slide.

In the case of a train of cars, it is not sufficient however merely to maintain the degree of adhesion utilization less than the maximum degree possible, it being essential that the degree of braking effect produced on all the wheels of all cars of a train be uniform. Uniformity of braking effect on all wheels of a train of cars can be pro,- duced or effected by causing the retarding force effective tangentially on each wheel to bear a substantially uniform ratio to or be a uniform percentage of the maximum tangential retarding force which may be imposed on the wheel, that is, by producing a uniform degree of adhesion utilization at each wheel.

Since under actual operating conditions, the weight of different cars and the passenger or freight load carried by the different cars varies, the various wheel-trucks on the same or different cars of a train bear or support different loads, and it follows that if uniform retarding forces are produced on all wheels of all wheel-trucks, a uniform braking effect, that is rate of retardation of all cars, will not be produced. As a result the cars will run toward each other or pull out away from each other depending upon whether a car in advance has the greater or lesser braking effect produced thereon respectively. By producing a substantially uniform braking effect on all cars of a train it will be apparent that there will be relatively little tendency for the cars to run in or pull out and that the shock to thecars as well as discomfort to the passengers incident to the running in and pulling out of the cars will be obviated.

Unless the braking on all wheels is such as to produce a uniform degree of adhesion utilization at each wheel, not only will there be uncomfortable shocks'as coupler slack adjusts to allow the more effectively braked cars to restrain the cars less effectively braked, but also it follows that as the braking effect is increased at a uniform percentage, those wheels most effectively braked with respect to the loads they carry will be the ones which will have the greatest tendency to A considerable disparity in the braking effectiveness as between different wheels on the same train naturally reduces the maximum retardation obtainable on the train without wheel slide.

pp n My invention accordingly includes means for measuring the actual braking effect produced on the wheels of each individual wheel-truck, and

means for each wheel-truck which is conditioned according to the load or weight carried by the individual wheel-truck, whereby the degree of retarding force produced by the brake devices on each wheel-truck is so controlled that a substantially uniform degree of adhesion utilization is effective on all wheel-trucks and a correspondingly uniform degree of braking effect produced on all cars of the train.

The coeflicient of adhesion between the wheels and the rails is different depending upon whether the wheels and the rails are dry, wet, oily, frosty or sanded. The condition of the wheels and the rails being uncertain, it is difiicult to provide a brake controlling system which will prevent wheels on a train from sliding under all conditions. My invention, therefore, includes means which is operative automatically upon' the occurrence of small or minor differences in the braking effect produced on the different wheels of I a wheel-truck While they still continue in roll, for so controlling the brakes associated with the different wheels as to tend to restore the uniformity of the braking effect produced on the different wheels. My invention, furthermore, includes means which is operative automatically upon the occurrence of major differences in the braking effect produced on the different wheels of the same wheel-truck, as where one wheel starts to slide and another wheel continues to roll, for releasing the brakes on the wheels which start to slide while at the same time maintaining the application of the brakes associated with the wheels which continue to roll without increasing such application.

In general, it is an object of my invention to so control the brakes on a vehicle or train of cars that a substantially uniform degree of braking effect is produced on each wheel at any given instant, thus minimizing likelihood of sliding the wheels.

More specifically it is an object of my invention to provide means local to each individual wheel-truck on a train of cars, which means is automatically conditioned to control the degree of adhesion utilization on all wheels of the individual wheel-trucks in accordance with the load carried by or supported on the corresponding wheel-truck so as to produce a substantially uniform degree of-braking effect on all cars of the train.

Another object is to provide a brake control means of the character indicated in the foregoing object and including means local to each individual wheel-truck and responsive to the torque force exerted on the brake devices associated withthe wheel-truck for measuring the actual braking effect produced on the wheels of each wheel-truck, whereby variations in the coefficient of brake shoe friction caused by variations in the braking force applying the brake shoes or by changes in the speed of rotation of the wheels may be automatically compensated for and a uniform degree of braking effect produced.

Another object is to provide a brake control system having means manually operative to select a uniform desired degree of adhesion utilization or degree of braking effect for all wheels, and

means local to each wheel-truck functioning automatically to control the brakes on each of the wheel-trucks individually in accordance with the load on the wheel-truck and in accordance with the degree of braking effect produced on the wheels of'the wheel-truck, to limit the maximum degree of braking effect on any of the wheels of the wheel-truck to that degree selected and to regulate the braking eifect on all wheels to the degree selected.

A further object of my invention is to provide means of the character indicated in the foregoing object, and including means operative in accordance with the greatest braking effect on any of the different pairs of wheels of an individual wheel-truck for controlling the brakes on all the wheels of the individual truck, to limit the maximum degree of braking elfect on any of the pairs of truck wheels to that degree selected.

A yet further object of my invention is to provide means of the character indicated in the two foregoing objects, including means responsive to small or minor differences in the degree of braking efiect on the different wheels of a wheeltruck for so controlling the braking means associated with the different wheels of the truck as to tend to equalize the degree of braking effect on the different wheels.

A still further object of my invention is to provide means of the character indicated in the foregoing object, and including means responsive to large or major differences in the degree of braking effect on the different wheels of each individual wheel-truck, such as occurs when one wheel slides and another continues to roll, for so controlling braking means associated with the different wheels on the truck as to automatically relieve the braking means associated with the sliding wheel for a predetermined time and then to cause the braking means to be re-applied for a predetermined time.

An additional object is to provide electrical braking means, such as an eddy current brake, in which the braking effect caused thereby reduces as the speed of thetrain reduces, and means for measuring the braking effect on a wheel or wheel axle produced by the electrical braking meansand operative automatically to control the electrical braking means so that it tends to maintain a substantially constant or uniform braking effect.

A yet additional object is to provide a braking system of the character indicated in the foregoing object and including a fluid pressure operated braking means of the friction type associated with each wheel with which an electrical braking means is associated and which is automatically controlled by the braking effect measuring means to supplement, that is compensate for, a decrease in the braking effect inherently produced by the electrical braking means, or in the event that the electrical braking means fails entirely.

A still further object is to provide a brake control system of the character indicated in the foregoing object and including novel means whereby the braking effect on a vehicle wheel or wheel axle may be measured or determined.

The above objects and other objects, which will be made apparent hereinafter, are attained by means of illustrative embodiments of my invention, which will be subsequently described and which are shown in the accompanying drawings,

wherein Fig. l is a diagrammatic plan view of a twoaxle wheel-truck, showing one embodiment of means for measuring the braking effect on the wheels of the truck and also the disposition and arrangement of means for registering the load on struction and the arrangement of an eddy current brake and a friction type fluid pressure operated brake associated with the armature shaft of each one of the driving motors shown in Fig. 1,

Fig. 4 is a sectional view, partly in section, taken on line 4-4 of Fig. 3, showing in further detail the construction and disposition of. parts of the brake device shown in Fig. 3,

Fig. 5 is a fragmentary view looking toward the right end of Fig. 4, showing the details of construction of the parts whereby mechanical connection between the supporting casing for the braking means and the means. for measuring the braking effect shown in Fig. 1, is established,

Figs. 6 and 7, taken together, constitute a diagrammatic view showing the electrical control circuits and other equipment comprising my invention as conditioned when the train of cars is running along the road with brakes released.

Fig. 8 is a chart indicating the condition of the individual switches making up the group switches shown in Figs. 6 and 7 for the various operating positions thereof,

Figs. 9 and 10 are. fragmentary views showing two different modifications in part of the system shown in Figs. 6 and 7.

Fig. 11 is a diagrammatic plan view of a twoaxle wheel-truck showing a modified arrangement including electrical circuits whereby means for measuring the braking. effect on a wheel axle is controlled and operated electrically,

Fig. 12 is a view taken on line 2--|2 of Fig. 11,

showing the details of the flexible gear or quill,

type gear drive and the arrangement and disposition of control mechanism in relation to the gear drive,

Fig, 13 is a sectional view taken on line |3-|3 of Fig. 12, showing in further detailthe arrange. ment of and circuit connections to the control mechanism shown in Fig. 11.

Referring to g. 1 of the drawings, my invention is illustratively shown in connection with a wheel-truck having a pair of axles l5 and i5 and gear wheels i1 and I8 respectively fixed thereto and adapted to be driven through the pinion gears I9 and 2| respectively, by the driving motors 22 and 23 respectively. For simplicity the truck frame is not shown, but it is to be understood that a truck frame of suitable character is provided. The motors 22 and 23 are fixedly mounted on the truck frame as by. suitable bolts (not shown) ex tending through the holes 24 in the bed-plate of the motors. The axles -|5 and I8 are suitably cradled on the truck frame to rock about the longitudinal axis of the armature shaft 25 of the associated motors so as to maintain a constant driving connection between the gear wheels I I1 and i8 and the pinion gears l9 and 2|, re-

spectively, upon movement of the axle relative to the truck frame. The purpose of fixedly mounting the motors on the truck frame instead of movably mounting the motors on the truck frame, as is frequently the case, is to enable the mechanical association with the motors of parts to be hereinafter described. I

Associated with .the armature shaft 25 of the motors 22 and-23 are brake devices 21 and 28 respectively, which are constructed and arranged as hereinafter described.

Suitably mounted on and fixed to the truck frame is an operating mechanism 3| having a casing 32 embodying in one portion thereof a device 33 for measuring the braking effect on the axles I5 and i8 individually and jointly and in another portion a device 34 for measuring the load on the wheel-truck and, which is similar in,

some respects to the variable load device described in Patent No. 1,670,391, to T. H. Thomas.

The brake devices 21 and 28 are similar, in some respects, to the brake device shown and described in my Patent No. 2,014,903, assigned to the assignee of this application. Since the brake devices 21 and 28 are identical in construction and operation, it-is deemed sufficient to describe only the brake device 21.

Referring to Figs. 1, 3 and 4, the brake device 21 comprises a brake drum 38 secured to the end of the armature shaft 25 of the motor 22 and, cooperating with'the external surface of the drum 38, a brake band 3! actuated into frictional engagement with the brake drum 38 by means of a pair of pressure cylinders 38. Each of the pressure cylinders 38 comprises a piston 39 having a piston rod 4|, the external end of the two rods 4| being connected, respectively, to opposite ends of the brake band3'l. Fluid under pressure is supplied to one side of each of the pistons 39 through a supply conduit or pipe 43 to actuate the piston to cause contraction of the band 31 around the outer surface of the brake drum 38. Upon release of fluid under pressure through the conduit 43, a spring 44 at the opposite side of each of the pistons acts to return the Distons and effectrelease of the band 31 from the drum 38. It should be understood that, if desired, other types of friction members may be employed instead of the band 31, the band 31 being merely illustrative of any suitable type of friction brake device.

The pressure cylinders 38 are suitably mount,-

ed on and secured, as by bolts 48, to a mou'nting plate or disc 41 having a central journal bearing 48 through which the armature shaft of the motor 25 extends for permitting rotation of the shaft relative to the plate 41. It should be understood that the bearing 48 may be a thrust bearingof any suitable type for holding the plate 41 against longitudinal movement on shaft 25. The mounting plate 41 has an upper portion 49 and a lower. portion 5i which both project in the direction of the end of the armature shaft 25 substantially parallel thereto, a cover-plate 52 being removably secured to the end of the portions 49 and 5| and having a'cen tral journal bearing 53 cooperating with the end of the armature shaft 25.

The brake band 31 is connected as by a rigid link 54, according to well known principles, to the lower portion 5| of the mounting plate 4' which link acts to cause an equal braking effect to be exerted on the brake drum 38 upon appliin cooperative alignment within the brake drum 38, the core piece 58 further having an opening 59 in the enlarged central portion thereof through which the armature shaft 25 extends.

Electro-magnet coils 62 mounted in insulated relation on and surrounding the core piece 56 are provided for setting up a magnetic field flux in and around the stator device.

It will be understood that the brake drum member 35 functions in a dual capacity, namely as an operating part of the friction brake previously described and also as an operating part, I

that is rotor, of an eddy current brake in cooperative relation with the stator device 55.

Integrally formed on or separably secured to the cover plate 52 of the brake device 27, in axial alignment with the armature shaft 25, is a T- shaped member, hereinafter referred to as the torque head 63.

It will be apparent that upon application of the brake band 3'! to the external periphery of the brake drum 36 or upon rotation of the brake drum through the magnetic field set up when the electromagnet coils 62 of the eddy current brake are energized, the mounting plate ll would rotate in the direction of rotation of the armature shaft 25 unless restrained from doing so. I therefore provide yielding means as hereinafter described, to resist movement of the plate ll, hereinafter designated the torque plate 37, so that the de- 'gree of movement ofthe torque plate may be taken as a measure of the braking effect produced on the armature shaft and consequently the axle associated therewith.

Since the degree of rotary movement of the torque plate i'l is in accordance with the brake ing effect on the armature shaft and axle, variations in the coefficient of friction between the brake band 31 and the brake drum 36, which coefficient is a function of the braking effect, are automatically taken into account, in the braking effect measured.

In accordance with my invention, the torque head 83 on the cover plate 52 of torque plate d'l serves to transmit the torque force tothe' measuring device 33, shown in Fig. 1, for either direction of rotation of the armature shaft 25.

Referring to Fig. 1, the device 33 comprises a coil spring 66 hereinafter termed the torque spring, disposed within a chamber 6! in the casing 32 andgsubject at opposite ends to the pposing forces of the torque exerted by the torque heads 63 of the brake devices 27 and 28 respectively whereby the rotary movement of torque plate 61 is yieldingly resisted, Any'suitable means may be provided for transmitting the torque from' the torque heads 63 to the torque spring 66, an illustrative mechanism being shown which comprises, in the case of the torque head 63 of the brake device 21, a bell-crank lever 69 pivotally mounted atthe' fulcrumthereof, as

by a pin H, on a projecting lug 12 formed on the casing 32, the outer end of one arm 73 of the bell crank lever having a rod i pivotally connected thereto as by a clevis 75' on the rod and a pin it which extends through the clevis and an elongated hole E1 in the end of the lever arm 13., The opposite end of the rod M has an enlarged end portion 18 formed thereon, which is 'in the shape of a semi-disc, the flat end of the semi-disc cooperatively engaging the side surface of the torque head 63, as shown in Fig. 5. The rod M is slidably mounted in suitable journal members 8| fixed to a portion 82 of the truck frame. The outer end of the other arm 83 of the bell-crank lever 69 has a rod 85, hereinafter termed a torque rod,.pivotally connected'thereto, as by a clevis 85 secured to one end of the rod 86 and a pin 85 extending through the clevis and an elongated hole 8! at the end of the lever arm 83. The other end of the rod 84 extends into the casing 32 and has an enlarged head portion 88 which engages one face of a follower member as, a recess 9! formed at the opposite face of the follower as being provided for receiving one end of the torque spring 66.

The mechanism, whereby the torque on the torque head 53 of the brake device 28 is transhaving at one end an inwardly extending flange 96 which engages the face of the follower 89, and at the opposite end an outwardly extending flange 97 which engages in contacting relation with an outwardly extending flange 98 on one end of the stop member 95. Disposed within the tubular stop member 94 and surrounding the head portion 88 on the torque rod 841 is a coil spring 99 which is interposed between the inwardly extending flange 96. of the stop member 96 andthe flange 98 of the stop member 95 for urging stop member 95 away from the stop member 95, the flange 91 on the stop member'9 3 being adapted to engage a stop lug it! on casing 32 to limit the movement of the stop member 95 away from the stop -member 95. A coil spring m2, which surrounds the stop member 95 and which is interposed between the flange 98 on the stop member 95 and an annular S110 111d6-|03 on the casing 32', urges the stop member 95 into contacting relation with the stop member 96, movement of the stop member 95 in the direction of the stop member 9d being limited by an outwardly extending flange Hi l at the end of the stop member 95 opposite to the flange 98', which flange IM is adapted to engage the shoulder Hi3.

In a similar manner the torque rod 8 5a has a pair of stop members 94 a and 95a arranged in concentric relation thereto in the manner corresponding to thatof the stop members 96 and 95 with respect to rod 84. The stop members 94a. and 95a and associated parts are identical in construction and arrangement to the stop members 9d and 95 already described, and it is deemed unnecessary to repeat the description thereof except to note that corresponding structure orelements are designated by corresponding numerals with the sufiix a.

Pivotally connected to the follower 89, as by a pin I06, is a link l0! and, similarly, pivotally connected to. the follower 89a, as by a pin N38, is a link M9, the other ends of the links l0? and H39 being pivotally connected as by a pin H0 on which is mounted a roller HI. A rod H3 is slidably mounted on the casing 32, as by brackets H4, and has an enlarged head portion M2 on The followers 89 and 89a each have a roller spring 86 to cause corresponding sliding movement of the rod I I3.

' Disposed within the chamber 61 of the casing- 32 and mounted in insulated relation on the cas-- ing are two groups HI and I22 of switches, group I2I comprisingaplurality of switches I23, I24,

I26, I26, and I21 (see Fig. 6) which are operated simultaneously by movement of the follower 89 and the group I22 comprising a plurality of switches I33, I34, I35, I36, and I31 (see Fig. '7)

. which are operated slmultaneousiyby movement in Figs. 6 and 7 respectively, and are thus simultaneously actuated. As indicated in Fig. 1, a lug I23 may be provided on each of the followers 89 and 89a which lug operatively engages the operating member of one of the individual'switches and thus actuates all of the operating members of the individual switches in the corresponding group I2I or I22 by means of the tie rod I29, or I29a.

The parts of the device 33 for measuring braking effect are normally positioned as shown in Fig. 1, the tension of the torque spring 66 being such that it normally overcomes the tension of the springs 99 and 99a so that the stop members 94 and 94a are urged into contacting relation with the stop members 95 and 95a, respectively. The tension of the springs I02 and I 021: is greater than that of the torque spring 66, and the stop members 95 and 95a are thus maintained in the extreme centerward position shown in Fig. 1. With the parts of the device 33 in the position shown in Fig. 1, the switch groups I2I and I22 are conditioned in a centralposition wherein the individual'switches thereof are open or closed, as indicated in the chart shown, in Fig. 8.

If the torque forces transmitted to the opposite ends of the torque spring 96, through the torque rods 84 and 84a are substantially equal, the spring 66 is contracted inwardly to an equal extent ,at the opposite ends thereof and the springs 99 and 99a thus become effective to urge the stop members 94 and 94a, respectively, in an inward direction to an extent determined by the engagement of the-flanges 91 and 91a with the stop lugs IOI and IOIa, respectively. With the stop members 94 and 94a positioned as just described, the inward recession of the followers 89 and 89a is such that the individual switches in groups I2I and I22 assume an inner position, the

' individual switches of each group being open or closed as indicated in the chart shown in Fig. 8. Further increase in the torque forces applied to opposite ends of the'torque spring 66 beyond the degree sufficient to permit maximum inward movement of the stop members 94 and 94a causes further compression of the torque spring 66 and a corresponding inward movement of the followers 89 and 8911 out of engagement with the flanges 96 and 96a of the stop members 94 and 94a respectively.

If the torque forces transmitted through torque rods 84 and 84a should become unbalanced, the torque spring 66 and the associated followers 89 and 89a will be shifted as a unit in the direction of the unbalanced force until such unbalance becomes counteracted by force exerted through the stop member 94 or 94a on the side of the lesser torque. Inasmuch as springs 99 and 99a are compressively tensioned a certain amount even when the stop members 94 and 94a are at their inward limit, it follows that the torque forces must be unbalanced more than a predetermined low amount sufllcient to overcome the tension of either spring 99 or 99a before the corresponding follower 89 or 89a may be shifted outwardly after reengaging the stop members 94 and 94a respectively. As the unbalance in the torque forces transmitted through the rods 84 and 84a increases above the predetermined low amount just described, no further outward movement of the followers 89 or 89a, will occur until the unbalance in the torque forces exceeds predetermined value considerably higher thanthe predetermined low value, at which either the spring I02 or I02a which is on the side of the lesser torque will be compressed. It will be seen, therefore, that group switches I2I and I 22 will both remain in their inner positions if the torque forces transmitted through the rods 84 and 84a differs only by a small amount, that the one of the group switches I2I or I22 on the side of the lesser torque will be actuated to its central position upon an intermediate amount of unbalance in the torque forces, and that the one of the group switches I2I or I22 on the side of the lesser torque will be shifted to its outer position upon the occurrence of a large amount of unbalance in the torque forces. The switch group I2I or I22 on the side of the greater torque force will, of course, remain in its inner position.

It is important to observe that the torque spring 66 is shortened in length an equal amount whether both of the brake .devices 21 and 28 are effective to cause equal and opposite torque forces to be applied to opposite ends of the spring 66 through the rods 84 and 84a or-whether either of the brake devices 21 and 28 acting alone, exert the same force as when both were effective. It follows, therefore, that the degree to which the spring 66 is shortened in length is a measure of the greater of the forces applied thereto from the brake devices 21 and.28 and accordingly that the degree of movement of the rod I I3, effected by relative movement of the followers 89 and 89a toward each other and the corresponding change in the angular position of the links I01 and I09, is a measure of. the greater of the torques and therefore of the greater of the braking effects exerted by the brake devices 21 and 28.

It is also important to observe that a difference in the torque forces applied to opposite ends of spring 66 causes bodily shifting of the spring 66 in the direction of application of the greater torque force and to an extentdetermined by the degree of the difference in the torque forces, the followers 89 and 89a being accordingly moved to actuate the switch groups I2I and I22 for purposes of brake control hereinafter described.

It should also be observed that the degree of rotary movement permitted to the torque head 63 associated with each of the brake devices 21 and 28 is limited to such a small angle and the system of levers including the rods 14 and 84 is so arranged as to prevent any wedging action. Furthermore, since the degree of such angular displacement of the torque head 63 from the normal position thereof is 'so small, the force applied by the torque head 63 to the head portion 18 (or 1. .1.1) on the rod 14 (or 1411) is maintained substantially equal to the entire torque force, with negligible variation in accordance with the cosine function of the angle of displacement of the torque head 63.

Referring to Fig. 1, the load measuring device 88 comprises a piston cylinder MI embodied in casing 82 andcontaining a piston I 52 having a piston stem I 33 which slides in a bore I68 of reduced diameter. In the bore I68 is disposed a dash-pot piston I and interposed between the piston I85 and the inner end of the stem I 38 is a coil spring M6 which acts normally to urge the piston I85 and the piston I82 into the position shown in Fig. 1, assuming no load on the truck except the weight of the car body. A lever M8 is pivotally connected at one end to the stem I88, through a connecting link I87, and a lever I69 is pivotally connected at one end to the free end of the lever I88 as by pin I5I. The opposite end of the lever I9 is secured to a rotatable shaft or pin I52, to which is also secured arg arm I58 which extends through an opening I II in the wall of the casing 32 to the exterior of the casing. The exterior end of the arm IE3 is pivotallyconnected to a rod I55, as by a ball-and-socket joint I 56, the rod I55 also being pivotally connected to the outer end of one arm of a bell-crank I57 (see Fig. 2), which is pivotally mounted at the fulcrum thereof, as by a pin I58, to a portion I59 of the car frame, the outer end of the other arm of the bell crankib'i having a roller I6I mounted thereon adaptedto engage a fixed surface I62 On a portion of the truck frame.

A lever I68 pivotally mounted on a fixed pin I65 carried by the casing 82 is pivotally connected at one end by a, link I66 to the piston I85, the

opposite end of the lever I68 having one end of a lever I67 pivotally connected thereto. The opposite or free end of the lever I67 carries a roller I68 adapted to roll along a guide I69 carried on the casing 82. The lever I64 carries an arm I7I which is provided at the free end thereof with a toothed segment I72. A lever I78 connects the levers I68 and I68, being pivotally connected at opposite ends thereof to the said levers.

A rocker arm I76 is pivotally mounted at the fulcrum thereof on the casing 82, as by a pin I8I, the outer end of one arm being provided with teeth for engaging the toothed segment I72, and the outer end of the other arm being pivotally connected to the outer end of a stem I75 of a piston I76 contained in a bore or chamber I77 in the casing 32. A coil spring I86, "in the bore I77, is so interposed between the piston I78 and the casing as to yieldingly urge the piston I76 in a direction to cause the teeth on the one arm of the rocker arm I78 to engage the toothed segment I72 to hold lever I68 against movement.

A weighing beam or lever I78 is provided and at a point intermediate the ends of lever I78 is pivotally connected one end of a lever I78, the opposite end of the lever I 79 being pivotally mounted on the casing 82, as by the same pin IIII on which the rocker arm I78 is mounted. The weighing beam I78 is so disposed as to contact the roller I68 on the lever I67 at a point diametrically opposite to the point of contact of the roller with the guide I69. The weighing beam I78 is provided at one end with an elongated hole I88 and at the opposite end with an elongated hole I88.

A rod I86, hereinafter termed a rack rod, is

pivotally connected at one end thereof to one end of the weighing beam I 78, as by a pin I87 extending through the hole I88 in the weighing beam, and is slidably mounted on the casing 82, as by one or more brackets I88, the opposite end of the rod I86 being provided with a gear rack portion I88 having cooperative engagement with a pinion gear I9I secured to the outer end of a shaft I 82 on which is carried a segment drum I88 (illustrated diagrammatically in Fig.- 6), of a controller device I86 suitably carried on the casing of the operating mechanism 8i A spring I98, interposed between the casing 32 and a collar I97 secured to the rack rod I86, normally urges the rod I86 inwardly of the casing 82 to position the segment drum I98 of the controller I86 in a normal position which will be hereinafter de-' scribed.

A rod 20! slidably mounted on the casing 82, as by one or more brackets 262, is pivotally connected at one end to the opposite end of the weighing beam I78, as'by a pin 263 extending through the hole I88. The opposite end of the rod 28! is provided with an enlarged rounded head 268, which is operatively engaged by the outer end of one arm of a bell-crank 886 pivotally mounted at the fulcrum thereof on the casing 32, the outer end of the other arm of the bellcrank 286' being operatively engaged by the end of the rod H3 opposite to that having the head I I2 which is engaged by the roller I I I.

A magnet valve device 288 is provided for controlling the supply and the release of fluid under pressure to and from the piston cylinder IM and piston chamber I77. The magnet valve device 268 .is normally energized, in a manner hereinafter described, so that fluid under pressure is vented from the piston cylinder MI and piston chamber I77 while the vehicle or'train of cars is in motion, and is deenergized when the vehicle or train of cars is brought to a stop for supplying fluid under pressure to the cylinder IIII and chamber I77.

Fluid under pressure, supplied to the piston chamber I77 from the supply pipe 2H through magnet valve 268 and pipe.and passage 2 I2 overcomes the force of the spring I88 opposing movement of the piston I76 and thus actuates the piston I76 to rock the rocker arm I 7d out of engagement with the toothed segment I72 on the lever arm I II. Fluid under pressure, supplied to the piston cylinder I lI from the pipe and passage 2I2 through the branch passage 2M moves the piston I82 to the left, as viewed in-Fig. 1, against the force of the spring I86.

The tension of the springs I66 and I88 is such that a higher fluid pressure per square inch is required to move the piston I 77 than to move the piston I62. Consequently the spring I86 maintains the rocker arm I76 in engagement with the toothed segment I78 on the'lever arm III so that the lever I68 is held against movement while the piston I412 moves inwardly. The lever I73, being secured to lever I68 is thus also held against movement, and the inward movement of the piston I52, occasioned by the pressure of the fluid supplied to the piston cylinder I II, rocks the lever I88 pivotally on the end of the lever I73 thus causing the leveri lfi to be pivotally moved about the pin I58 through an angle in a clockwise direction, as viewed in Fig. 1. The lever M9, in turn, effects corresponding rotation of the pin 52 and arm I53, and rod IE5 is thus moved upwardly in Figure 1 and in the left-hand direction in Figure 2 to cause rotation of the bell-crank I57 in a clockwise direction, as viewed in Fig. 2, to move the .roller IIII into engagement with the surface I62 on the truck frame.

Subsequent to the operation Just described, the pressure of the fluid supplied to the chamber I11 becomes effective tomove the piston I18 against the resstance of the-spring I88 and thus effects movement of the rocker arm I14 out of engagement with the toothed segment I12 on- I51 is accordingly rotated in a counterclockwise the right, as viewed in Fig. 2.

Since the piston I42 is held in its inner position by the pressure of the fluid supplied to the piston cylinder I, the movement of the rod I55, with an increase in, load, through the arm I 58 and lever I 49 eilects a counterclockwise movement of the lever I48 about the point of pivotal connection to the link I41 and thus, through the lever I18, effects a counterclockwise movement ofthelever I64 about the fixed pin I65. The lever I 61 is thus moved, with the lever I64, to the left as viewed in Fig. l, to adJust the position of the fulcrum roller I68 in accordance with the load on the wheel-truck.

It will be apparent that if the load on the wheel truck is decreased. the spring I46 will urge the dash-pot piston I45 to the left, as viewed in Fig. l, and consequently effect clockwise rotation of lever I64 on the pin I65 so that the fulcrum roller I68 will accordingly be moved to the right, as viewed in Fig. l, and the rod I55 will be moved to the left, as viewed in Fig. 2, until the roller I6I on the rocker arm', I51 again contacts the truck portion I62.-

When'motionof the vehicle or train of cars is initiated and fluid under pressure is released from the piston chamber I11 of the piston cylinder I, the spring I80 becomes first effective, ,as the fluid pressure is decreased, to rock the rocker arm I14 into engagement with ment I12 to lock the lever arm I1I against movement. Subsequently, as the fluid pressure furdirection to effect movement of the rod I55 to ther decreases, the spring I46 moves piston I42 to the right, as viewed in Fig. 1, and. since the lever I13 is held against movement, the lever I48v is rocked about the end of the lever I18 to cause a counterclockwise movement of the lever I49 and the arm I53, which results in counterclockwise movement of the bell crank I51, as'viewed in Fig. 2, so that the roller I6I is moved out of engagement with the contact surface I62 on the truck frame. The load measuring device 84 is thus rendered unresponsive to the normal relative movement of the car'fra-me portion I58 and the truck frame portion -I62 during the time that the vehicle or train of cars is in motion.

The cooperative relation of the device 88 for measuring braking effect, and the load measuring device 84 should now be apparent. Whenever the rod H8 is moved to the right, as viewed in Fig. 1,

. which as will be explained hereafter in greater detail occurs upon an application of the brakes to either one or both the axles I5 and I6, the bell-crank lever 296 is rocked in a clockwise direction and thus through the rod 2III causes a counterclockwise rocking movement of the weigh- -ing beam I18 about the roller I68 as 'a fulcrum.

the rack rod I 66 being accordingly moved aga nst "the force of the spring 196 to cause rotation of the segment drum of the controller I94. The tension of the spring I96 is such that for a given posithe toothed segtion of the fulcrum roller I68 and a given force urging the red II8 to the right, a corresponding movement of the segment drum of the controller I94 willbe effected. I

If the fulcrum roller I69 is positioned, inaccordance with the degree of the load on the wheel-truck, to the left of the positionshown in Fig. l, a greater force must necessarily be applied to the rod II8 to effect the same degree of rotation of the segmcnt drum of the controller I94, due to the shortening of the moment arm extending from the fulcrum point of contact between the roller I68 and the weighing beam I18 to the pin 268.

Conversely, if the fulcrum, roller I68 is positioned in any position to the right of that shown in Fig. 1, as for a decrease in the load on the wheel-truck, a lesser force is required to be ap plied to the rod II8 to effect the same degree more main reservoirs, such as the reservoir 22I,

disposed on one or respectively on more than one of the cars of the train, a main reservoir pipe 222 connected to the main reservoir 22I and extending in the usual manner throughout the length of the tra n. the pipe! also being connectedtogother main reservoirs if employed on other cars, a plurality of control wires 224, 225, 226, 221 and 228 extending in usual manner throughout the length of the train, a manually operable brake switch device 229 located on the control car of the train and adapted to effect ener-" gization of train wires 224 to 228, a vibration relay device 28I of the type shown and described in my copending application Serial No. 734,781 filed July 12, 1934, and ass gned to the assignee of the present application, and a suitable generator 23'! located on one of the cars of the train and adapted to supply power to all of the cars through a train wire 288 extending throughout the length of the train, the wire 288 being connected to one terminal of the generator and the other terminal of the generator being connected to ground, as.

shown, or to a return train wire if desired. Although wire 288 is illustrated as being energized from generator 282, it is to be understood that it might, instead, be. energized from a trolley or third tall. the same as are the-driving motors.

.An electromagnet switch device 284, which is I controlled by the vibration relay device 28I in a manner hereinafter described, controls the con nection from a suitable source of electrical energy,

such as a battery 285, to another train wire 286 which extends, in usual manner, throughout the length of the train. eachindividual magnet valve device 288 associated with the load measuring device 84 on each wheel-truck being connected to and energized .by current supplied over the wire 286. as'hereinai'ter described.

- An emergency relay switch device 288, located preferably on the control car of the train, is

provided for connecting train wires 221 and 223 to the'battery 285 independently of the brake switch device 229. A deadmans" switch device the length of the train, the wire 522 being contrain, control the circuit of the magnet coil 242 of the relay device 238, the devices 239 and 24! being effective to interrupt the flow of current through a train wire 243 which extends throughout the length of the train and which is grounded at its termination on the last car in manner not shown. If a battery return wire is employed, then the wire 243 is connected thereto on the last car instead of to ground.

A signal lamp 5! I, located on the control car. has one terminal connected to ground and the other to a train wire 522 extending throughout nected to battery upon the occurrence of wheelsliding on any of the wheel-trucks, in the manner hereinafter described, the circuit being thus closed through the lamp to cause the lamp to be illuminated and indicate the wheel-sliding condition.

For the sake of simplicity, additional brake operating and control equipment local to each in dividual wheel-truck, on every car of the train is illustrated for one wheel-truck only.

The local brake control equipment for each of the brake devices 21 and 28 associated respectively with the wheel axles l5 and !6 of each wheel-truck are identical in construction and the local brake control equipment for the brake device 21 is thus illustrated in detail in Fig. 6 whereas the local brake control equipment for the brake device 28 is shown merely in outline form in Fig. '1. Referring then to Fig. 6, the local control equipment for the brake device 21 includes an application magnet valve device 248, a release magnet valve device 249, a pneumatic switch device 25!, a volume reservoir 252, a fluid pressure operated relay device 253 for controlling the supply and release of fluid under pressure to and from the pressure cylinders 38 of the brake device 21, a rheostat 254 for controlling the I degree of the current supplied to the coils 62 of the eddy current brake portion of brake device 21 and operated by a fluid pressure responsive device, such as the diaphragm device 255, through the medium of a pressure-limiting device 256, and a relay device 251 for controlling a circuit including the rheostat 254 and the coils 82 of the eddy current brake device previously described.

The brake control equipment individual to each of the brake devices 21 and 28 also includes a pneumatic switch device 259, a timing reservoir 26!, a fluid pressure operated relay device 262 for controlling the supply of fluid under pressure from a local reservoir 263 to another pneumatic switch device 264,.and a magnet valve device 285 for controlling the supply of fluid under pressure to the pneumatic switch device 259 and the relay device 262. The application and release magnet valve devices 248 and 289 are controlled, as will be hereinafter described in detail, by the controller device !94 previously mentioned and associated with the load measuring device 34.

The application magnet valve device 248 comprises an electromagnet 21! and a valve 212 actuated by the electromagnet 21! through a stem 213. The valve 212 is disposed in a chamber 214 which is in constant communication with the pipe 222 through a branch pipe 215, and when the electromagnet 21! is deenergized the valve 212 is yieldingly urged into seated relation on 1 an associated valve seat by a coil spring 216 interposed between the valve and a screw plug 211 closing the chamber 214. When the e ctromagnet 21! is energized the valve 212 is unseated against the force of the spring 216 and communiby the electromagnet 28! through the medium of E a stem 283. The valve 282 is disposed in a chamber 284 constantly open to atmosphere through a port 285 and is provided with a fluted stem 281 which extends through a bore 288 in the casing into a chamber 288. When the electromagnet 28! is deenergized the valve 282 is unseated from its associated valve seat to establish communication between chambers 288 and 288 through bore 285 by a coil spring 289 in the chamber 288, which spring is interposed between a collar on the end of the fluted stem 281 of the valve 282 and a screw plug 29! closing the chamber 288. Chamber 288 is constantly in communication with pipe and passage-219 through a branch passage 292 and thus, when the valve 282 is unseated, the passage and pipe 219 is connected to atmosphere.

The pneumatic switch device 25! comprises a casing 294 having a piston chamber 295 containing a piston 296 which actuates a movable switch member 291 through the medium of a stern 298. A coil spring 299 interposed between one face of the piston and the casing 294 normally urges the piston 298 in such direction as to move the switch member 291 into circuit-opening position. Fluid under pressure is supplied to the piston chamber 295 from the pipe 219 through a branch pipe 38!, and-the tension of the spring 299 is such that when the pressure of the fluid supplied into the magnet valve device 248 attains a degree, such as three pounds per square inch, the piston 296 is actuated against the resistance of spring 299 to move the switch member 291 into circuit-closing position.

The pneumatic relay device 253 comprises a casing 383-containing a piston 384 havinga chamber 385 at one side thereof, which chamber is constantly subject to the pressure of fluid in local reservoir 252 through a branch pipe 386 which opens into pipe 219 leading to the reservoir 252, and a chamber 381 at the opposite side thereof in which is disposed a slide valve 388 adapted to be operated by the piston through the medium of a stem 389. The stem 389 is provided with spaced collars or lugs 3l8 and 3!! adapted to engage opposite sides of the slide valve 388 and so spaced as to permit a certain amount of movement of the stem 389 relative to the slide valve 388. The stem 389 is provided at the end thereof with a collar 3l2 which extends into a reduced portion of the chamber 381, and a coil spring 3L3 disposed in the reduced portion of the chamber 381 between the collar 3l2 and the casing 383 resists movement of the piston 384 and slide valve 388 to the right, as viewed in Fig. 6, until the pressure of the fluid supplied to the piston chamber 385 exceeds a predetermined degree, such as forty pounds per square inch.- The slide valve 388 is normally positioned, as shown, to lap or cover an inlet passage 3l8 to which the pipe 219 is connected and to uncover an atmospheric exhaust passage 3l5 opening into the chamber 381. The

supply conduit 43 leading to the pressure cylinders 38 of the braking device 21 opens into the chamber 381 and, with the exhaust port 3l5 unthrough inlet port M4 on the seated face of the slide valve 388,a spring biased roller 3! 6 is provided in 1well known manner for engaging the upper surface of the'slide valve 388. c

When? the pressure in chamber 305 is sumcient to cause the slide valve 368 to be shifted to the right, the slide valve first laps or covers the exhaust port 3!5 and then opens or uncovers the inlet port 3, thereby causing fluid unde'r pressure to be supplied from local reservoir 252, through pipe 219 and port 3 into slide valve chamber 381 and thence to' the pressure cylinders 38 through supply conduit 43. When the brake cylinder pressure in chamber 301 plus the force relay device 251. A piston 324 contained of spring 3l3 becomes slightly greater than local reservoir pressure the slide valve 308 is shifted back'to the left to lap the inlet port 3l4 without uncovering the exhaust port 3!5. Upon a decrease in local reservoir pressure, the slide valve 388 is shifted further to the left to the position shown, and fluid under pressure is released from thecylinders 38 until the combined force of spring 3!3 and fluid pressure in chamber 301 is less than the local reservoir pressure. Slide valve 308 is then shifted to the right to lap the exhaust port 3|5 without opening the inlet port 3. The valve device 253 thus regulates the pressure of fluid supplied to the cylinders 38 to a substantially uniform value, such as forty pounds per square inch, less than the local reservoir pressure, depending upon the tension of spring'3 l3.

The rheostat 2-54, illustrated as of the carbonpile type, comprises a tubular casing 3l8 of insulating material suitably mounted on the car frame or wheel-truck and containing a plurality "of carbon blocks or discs 3l9, one end block being connectedto a wire 32! leading to the eddy current brake coil 62 of the brake device 21 and the other end block being connected by wire 322 to one of the switch contact members 323 of the in the casing 3l8 at one side of the stack of carbon blocks 3!!! and suitably insulated from the blocks, as'by an insulating washer 328, is provided with a stem 325 extending to the exterior of the casing 3! 8 and having a cup shaped portion 326 constituting the casing of the pressure-limiting device 256.

The device 255 may be of any suitable character for applying or transmitting pressure and is illustrated as comprising a separable casing 328 having a flexible diaphragm 329 clamped at its periphery between the parts of the casing 328 and having a chamber 33! at one side thereof which is supplied with fluid under pressure from the pipe 219 through a branch pipe 332. Disposed in a chamber 333 at the opposite side of the diaphragm 329 is a follower 334 having a stem 335 extending to the exterior of the casing 328. The stem 335 has a collar 336 secured to the end thereof and contained in the casing 326 of the pressure-limiting device 256. A coil spring 331 contained within the casing of the device 256 and interposed between the collar 336 and the casing is so tensioned that when the pressure of the fluid in the chamber 33! acting on the diaphragm 329 exceeds a predetermined value, such as forty pounds per squareinch, which pressure is substantially the same pressure as that required before operation of the relay device 253 is permitted, the spring 331 yields sufliciently to per-- Init follower 334 on stem 335 to engage the casing 328 of pressure device 255 and thus effectively carbon blocks 3l9 of the rheostat 254.

nected to the I 338.

The reservoir 252 is provided for adding volume capacity to the chamber 33! of the diaphragm device 255, piston chamber 295 of the pneumatic switch device 26! and the piston chamber 385 of the relay device 253, the reservoir being conplpe 2'19'through the branch pipe The pneumatic switch device 259 is similar to the pneumatic switch device 25! and comprises a casing 34! containing a piston 342 operative to move a switch member 343 through a stem 344, the piston 342 being normally biased to a position for moving the switch member 343 to circuitopenin'g position by a coil spring 345 interposed between one face of the piston 342 and the easing 34!. When fluid under pressure is supplied to a chamber 346 at the opposite side of the piston 342, the piston 342 is actuated, against the force of the spring 345,to move the switch member 343 to circuit-closing position.

The magnet valve device 265 comprises an electromagnet348 adapted to actuate a pair of oppositely seating valves 349 and 35! through the medium of a stem 352. The valve 349 is disposed in a chamber 353 which is constantly open to atmosphere through a port 354, and the valve 35! is disposed in a chamber 355 which is in constant communication with the main reservoir pipe 222 through a pipe 356 and branch pipe 351. The valves 349 and 35! are'each provided with fluted stems which meet in end-to-end contacting relation within a chamber 359 intermediate of the chambers 353 and 355, the chamber 359 being connected to a pipe 36! which is connected to the piston chamber 346 of the pneumatic switch device 259 through a branch pipe 362. A coil spring 363 disposed within the chamber 355 and acting on the valve 35! yieldingly urges the valve 35! into seated position and the valve 349 into unseated position when the electromagnet 348 is deenergized. When the electromagnet 348 is energized, the valves 349 and 35! are actuated, against the force of the spring 363, into seated and unseatedv positions respectively. It will be apparent, therefore, that the magnet valve device 365 controls the supply of fluid under pressure from the main reservoir pipe 222 into the pipe 36! and the exhaust of fluid under pressure from the pipe 36!.

The valve device 262 comprises a casing containing a piston 366 having a stem 361 for actuating a pair of oppositely seating valves 368'and 3,69 contained within a chamber 31! in the easing, which chamber is constantlyconnected to the reservoir 263 through a pipe 312. Each of the valves 368 and 369 is provided with a fluted stem at one side thereof, the stems meeting in contacting end-to-end relation within the chamber 31!. The valve 369 is also provided with a fluted stem'at the other side" thereof which extends through a bore in the easing into a chamber 314. A coil spring 315 disposed in the chamber 314 and acting on the end of the fluted stem of valve 369 yieldingly urges the valves 368 and 369 into seated and unseated positions, respectively,

chamber 314, which is in constant communication with the main reservoir pipe 222 through the pipe 356, to the chamber 31! and the reservoir 263. At one side of the piston 366 is a chamber 316 which is supplied with fluid under pressure from the pipe 36! to actuate the piston 366 to move the valves 368 and 369, against the force of the spring 315, to unseated and seated positions respectively. When the valve 368 is unseated it establishescommunication from the chamber 31! to a chamber 311 at the other side of the piston 366, the chamber 311 being constantly connected to atmosphere through a pipe 318 havin ga restricted portion or choke 319 at the end thereof.

The reservoir 26! is connected to the pipe 36! through a branch pipe 38! at a point between the connection of the branch pipe 362 to the pipe 36! and the valve device 262. The pipe 36! is provided, at the portion thereof between the points of connection of the branch pipes 362 and 38! thereto, with a restricted portion or choke 382, whereby the charging of the reservoir 26! and the operation of the valve-device 262 is calculated to take place a predetermined time interval after the operation of the pneumatic switch device 259.

The pneumatic switch device 264 comprises a casing 384 containing a piston385 having a stem 386 for actuating a pair of movable switch members 381 and 388 suitably insulated from each other. At one side of the piston 385 is a coil spring 389 for biasing the piston 385 to a position such that the switch member 381 is in circuitopening position and the switch member 388 is in circuit-closing position in engagement with a fixed contact member 39!. At the opposite side of the piston 385 is a chamber 392 which is supplied with fluid under pressure through a branch pipe 393 connected to the pipe 318 at a point between the choke 319 and the valve device 262. When the piston 385 is actuated by the pressure of the fluid supplied to the chamber 392, the switch member 381 is moved to circuit-closing position and the switch member 388 is moved to disengage the contact member 39! and to engage another contact member 394.

The volume .of the reservoir 263 and the size of the choke 319. are such that when the valve device 262 is operated to supply fluid under pressure from the reservoir 263 into the pipe 318 the piston 385 of the pneumatic switch device 264 is actuated to the position last described and maintained in such position for a predetermined length of time determined by the time required for the pressure in the reservoir 263 and effective in chamber 392,0n the piston 385 to be sufficiently reduced through choke 319 to permit the spring 389 to move the piston 385 and switch members 381 and 388 to the normal position shown in Fig. 6.

Since the control equipment individual to the brake device 28 associated with the axle I6 is a duplicate of that desecribed above for the brake device 21 associated with the axle I5, the dedescription of the parts shown in Fig. 7 for the brake device 28 is not repeated except to note that corresponding devices or elements are designated by numerals corresponding to those employed for the brake device 21, with the suffix a added thereto.

Referring to Fig. 6, the brake switch device 229 may be of any suitable character adapted for manual operation, the device being illustrated diagrammatically as comprising a plurality of fixed contact members 48!, 482, 483, 484, 485 and 486 arranged in a row, and a movable stepped contact segment 481 adapted tobe manually moved to the right, as viewed in Fig. 6, to connect the contact member 48! to the contact members 482, 483, 484, 485 and 486 in succession depending upon the degree of displacement of segment 481 from the normal release position indicated in the drawing. The contact member 48! is constantly connected to the positive terminal of the battery 235 by wires'or conductors 488,

489, M8 and 4H, and the train wires 224, 225, 226, 221 and 228 are connected, respectively, to the contact members 482, 483, 484, 485 and 486. It' will thus be apparent that depending upon the degree of operative movement of the brake switch device 229 from the normal release position, one or more of the wires 224 to 228 will be connected to the positive terminal of the battery 235.

The controller I94, associated with the load measuring device 34 shown in Fig. 1, is shown diagrammatically in Fig. 6 as comprising a rotary drum I93 on which are mounted in insulated relation a pair of stepped contact segments 4I3 and 4I4, the segments being shown in developed form. The controller I94 also comprises a group of fixed insulated contact members 495, 4I6, 4I1, 4! 8, M9 and 428 arranged in a row and all normally engaged by the segment 4I3. The contact members 4I5, M6, 4111, M8 and 4I9 are constantly connected to the train wires 224, 225, 226, 221 and 228, respectively, by branch wires 42!, 422, 423, 424 and 425, the contact member 428' having a wire 426 connected thereto which is in turn connected to a wire 421 connected 'to the contact member 39! of the pneumatic switch device 264 and contact member 39Ia of the pneumatic switch device 264a.

The controller I94 further comprises a group of fixed insulated contact members 43!, 432, 433, 434, 435 and 436 arranged in a row and all normally engaged by the contact segment 4I4. The contact members 43!, 432, 433, 434 and 435 are constantly connected to the train wires 224, 225, 226, 221 and 228, respectively, by branch wires 438, 439, 448, 44! and 442, the contact member 436 having a wire 444 connected thereto whichis in turn connected to a wire 445 leading to one terminal of the electromagnet of the release magnet valve device 249 and also to one terminal of the electromagnet of the release magnet valve device 249a.

The contact members M5, M8, M1, M8, M9 and 428 'are so disposed with respect to the contact segment 4I3 that the contact member 428 remains in constant engagement with the segment 4I3 while the contact members M5, M6, M1, M8 and M9 are successively disengaged therefrom, in the order named, upon rotation of the segment drum I93 from its normal position by operation of the operating mechanism 3! shown in Fig. 1.

The contact members 43!, 432, 433, 434, 435 and 436 are so disposed with respect to the contact segment 4I4 that contact member 436 is constantly in engagement with the segment 4I4. whereas contact members 43!, 432, 433, 434 and 435 are successively disengaged therefrom in the order named upon rotation of the segment drum I93 out of its normal position.

It is important to note that the contact segments M3 and M4 are not identical, the contact segment 4I3 disengaging its associated contact members M5, M6, M1, M8 and M9 whereas corresponding contact members 43!, 432, 433, 434 and 435 remain in engagement with the contact segment 4 I4 for the same degree of rotary movement of the segment drum I93. For example, for 'a given rotary movement of the segment drum I93 the contact segment 4I3 will disengage the contact member 4I5 whereas the contact member 4I4 still remains in engagement with the contact member 43! which is connected to the same train wire, namely wire 224, as is the contact member 4I5. I

The terminal of the electromagnet of the mag- 'tromagnet coil 414 net valve device 249 opposite to that to which the wire 446 is connected and one terminal of the electromagnet oi the' application magnet valve device 246 are connected by common wire I which is in turn connected by a. wire 462 to the movable switch member 343a of the pneumatic switch device 2694, the other terminal of the electromagnet of magnet valve device 243 being connected by a wire 396 to the switch member 366 of pneumatic switch 264. 463, connected to the wire 452, is normally connected to a ground wire 464 through the series related switches I26 and I25 0! the group I2I.

In a similar manner corresponding terminals of the electromagnets o! the magnet valve devices 246a and 249a (see Fig.7) are connected by a common wire 45Ia, which is in turn connected to a wire 4520 leading to and connected to switch member 343 of the pneumatic switch device 259, the remaining terminal of the application magnet valve device 246a being connected by a wire 3960 to switch member 366a of pneumatic switch 264a. Also, a branch wire 463a connects wire 452a toground wire 454 through the series related switches I36 and I35 of the group I22.

The magnet valve, device 266 (see Figs. 1 and 7), one of which is .associated with each of the load measuring devices 34 for the wheeltrucks may comprise an electrcmagnet 451 for actuating a. pair of oppositely seating valves 466 and 469 through the medium of a stern 46I. The valves 456 and 459 are contained within a chamber 462 to which the pipe 2I2 leading to theload measuring device 34 is constantly connected, the valves 456 and 459 engaging each other in contacting relation within the chamber 462. The valve '469 is provided with a fluted stem 463 which extends through a bore in the easing into a chamber 464 which is constantly connected to the main reservoir pipe 222 by branch pipe 2| I, a biasing spring 466 within the chamber 464 cooperating with the end oi the fluted stem 463 for yieldingly urging the valves 466 and 469 into seated and unseated positions, respectively, on associated valve seats, when the electromagnet 451 is deenergized. When the electromagnet 451 is energized, the valves 456 and 459 are shifted against the force of the spring 466 into unseated and seated positions respectively. The valve 469, when in seated position, cuts of! communication between the chambers 464 and 462 and the valve 456, when. unseated, opens communication from the chamber 462 to an atmospheric chamber 466. It will thus.

be apparent that the magnet valve device 266;

controls the supply and release of fluid under pressure to and from the pipe 2I2 leading to the load measuring device 94.

The circuit for energizing the eleetromagnet 461 of the magnet valve device 266 is controlled by the relay 234, one terminal or the electromagnet 461 being connected to ground through a wire 469, the other terminal being connected v by a wire "I to the train wire 236, which is in turn connected by a wire 412 to a fixed contact member 413 of the relay 234. The relay 234 comprises an electromagnet coil 414 for actuating a movable bridging member 415 to interrupt the connection between the contact member 413 and 236 through wires 6 and H I. When the elecis 'deenergized or energized insufliciently, the bridging member 415 falls A branch wire 1 1 into contacting relation with the contact members 413 and 416, thereby connecting train wire 236 to the positive terminal of battery 236 and completing the circuit for energizing the electromagnet 461 oi the magnet valve device 233.

Energization and deenergization or the relay :34 is controlled by the vibration relay device 3| The vibration relay device 23I comprisu a tubular casing 416 of insulating material threaded internally at the opposite ends thereof for receiving metallic conducting screw plug members 419 and 466 respectively. The inner ends. of the members 419 and 463 are coated, as by electrolytic deposition or by brazing, with some highly conductive material and a quantity of granules material, such as carbon, between in the casing 413. The screw plug member 466 is connected to the positive terminal oi the battery 236 by wire H I and the screw plug 419 is connected to one terminal of the coil 414 of the relay 234 by wire 464, the other terminal of the coil 414 being grounded by wire 465.

The vibration relay 23I is mounted on some part of the vehicle or train of cars which is subject to appreciable vibration during motion 01' the vehicle or train of cars.

When motion of the vehicle or car is stopped, the carbon granules I settle to the lower portion 01' the space between the screw plugs 419 and 436, the resistance through the granules between the screw plugs 419 and 466 being then such that the current through the coil 414 or the relay 234 is sufficient to pick up the bridging member 416 and thus interrupt the circuit for energizing the train wire 236 and accordingly that of the electromagnetof the magnet valve device 266 for each of the load measuring devices 34 for the wheel-trucks. When the vehicle is in motion the carbon granules I are vibrated and consequently separated, the resistance in the circuit of the coil 414 of relay 234 beingthus so increased as to cause the current through the coil 414 to be sufllciently decreased as to be ineffective to maintain the bridging member 416 in pickedqip or circuit-opening position. The circuit for energizing the electromagnet of the magnet valve device 266 on all the wheel-trucks is thus completed, when the vehicle or train oi. cars is in motion, by the dropping out of relay 234 to circuit-closing position.

I of conducting is contained there-- OPERATION (a) Substantial equality of braking eflects on difierent wheels train of cars stopped, fluid under pressure is also supplied from the pipe 222 to the piston cylinder I and piston chamber I11 of the loadmeasuring device 34 under the control of the magnet valve device 266 for each'wheel-truck, therebyrcausing the roller IN on the bell crank I61 (see Fig. 2) to be moved into engagement with the contact surface I62 on the truck frame in readiness for adjusting the load responsive .15 411 such as silver,

device 34 in accordance with the load placed on the wheel-truck.

When the vehicle or train of cars is in motion, the magnet valve device 298 for each wheel-truck is energized in the manner just previously described, to effect the release of fluid under pressure from the piston cylinder MI and piston chamber I11 of the load responsive device 34 to cause latching of the load measuring device 34 in position and retraction of the roller I6I on the bell-crank I51 out of engagement with the contact surface I62 on the truck-frame.

With the vehicle or train of cars running along the road, the brake switch device 229 being in the release position thereof and the magnet valve devices 208 associated with the load measuring devices 34 all being energized, in the manner just described, if it is desired to effect a service application of the brakes, the brake switch device 229 is operated to select a desired degree of adhesion utilization or of braking eifect, the position of the switch 229 being such for example, as to connect the three train wires 224, 225 and 226 to the positive terminal of the battery 235 in the manner previously described.

The application magnet valve device 246 and release magnet valve device 249 for the brake device 21 and the application magnet valve device 248a and the release magnet valve device 249a for the brake device 28 are accordingly energized in the following manner. The circuit for the release magnet 249 extends from the positive terminal of the battery 235 through wires 4H, M9, 499 and 498, brake switch device 229, in parallel through the train wires 224, 225, 226 and branch wires 438, 439, 440 to the contact segment M4 on the segment drum I93 of the controller I94, and thence by Way of wires 444 and 445, electromagnet 28I of the magnet valve device 249, wires 45I, 452 and 453, switch I26 of the group I2I, wire '49I, switch I25 andwire 454 to ground, the return circuit to the groundednegative terminal of the battery 235 being thus established.

The circuit for energizing the application magnet valve device 248 extends from the contact segment 4I3 of the controller I94, (the contact segment 4I3 being connected by the branch wires 42I, 422 and 423 to the train wires 224, 225 and 226 and thus to the positive terminal of the battery 235) through wires 426 and 421, contact member 39I of the pneumatic switch device 264,switch member 388 of the device 264, wire 399, electromagnet 21I of the application magnet valve device 248, and subsequently to ground through the wires 45I and 452 as described for the release magnet valve device 249.

The circuit for energizing release magnet valve device 249a extends from the positive terminal of the battery 235 to the contact segment 4I4 of the controller I94 the same as described for the release magnet valve device 249 and thence through wires 444 and 445, electromagnet 28kt of the magnet valve device 249a, wires 45I a, 452a and 453a, switch I36 of group I22, wire 49Ia, switch I35, and wire 454 to ground.

The circuit for energizing the application magnet valve device- 248a extends from the positive terminal of the battery 235 to the contact segment 4I3, as described for the application magnet valve device 249, and thence through wires 426 and 421', contact member 39Ia of pneumatic switch device 264a, switch member 388aof device ground byway of wires 45m and 4520, as described for the release magnet valve device 249a.

Upon the energization of the magnet valve devices 248, 249, 248a and 2490, as just described, fluid under pressure is supplied from the main reservoir 22I to the local reservoirs 252 and 252a through the pipe 222 and the'branch pipes 215, 215a. and the pipes 219, 219a under the control of the respectively associated magnet valve devices in the manner previously described. When the pressure of the fluid in the local reservoirs 252 and 252a as well as in the pipes 219 and 219a. reaches a predetermined low value, such as three pounds per square inch, the pneumatic switch devices 25! and 25in. are actuated to circuitclosing position for energizing the'relays 251 and 251a, respectively. The circuit for energizing the relay 251 extends from the train wire 236, which is connectedto the positive terminal of the battery 235 by relay 234 as previously described, through I coil 496 of relay 251 and wire 491 to ground.

The circuit for energizing the relay 251a extends from the train wire 236 through wires MI and 498, switch member 291a of the pneumatic switch device 25Ia, fixed contact member 494a of the switch device 25m, wire 495a, coil 496a ofthe relay 251a, and wire 491a to ground.

The circuits for energizing the eddy current brake coils 62 and 62dof the brake devices 21 and 28 are accordingly established due to the energization of the relays 251 and 251a, respectively. The circuit for the coil 62 of the brake device 21 extends from train wire 23' which it will be remembered is connected to one terminal of the generator 232, through a wire 59 I, a. fixed contact member 502 of the relay 251, movable bridging member 503, contact member 323 of the relay 251, wire 322, rheostat 254, wire 32I, and coil 62 of the brake device 21 to ground.

In a similar manner the circuit for energizing the coil 62a for the brake device 28 extends from the train wire 233 through branch wire 56 la, fixed contact member 502m of the relay 251a, contact bridging member 593a, fixed contact member 323a of relay 251a, wire 322a, rheostat 254a, wire 32Ia, and coil 62a to ground.

Application of the eddy current brake of brake devices 21 and 28 to effect retardation of axles I5 and I6, respectively, is accordingly initiated, the exciting current supplied through the coils 62 and 62a of the brake devices 21 and 28 increasing with the decrease in-resistance of the rheostat devices 254 and 25411, respectively, occasioned by the increasing pressure of the fluid in the local reservoirs 252 and 252a acting on the diaphragm within the diaphragm devices 255and 255a.

Assuming for the purposes of the present operation that the braking effect produced on the axles (Fig. 1) causes a substantially equalinward move- 'ment' of the followers 89 and 8911 against the resist ing force of the torque spring 66, the switch groups I21 and I22 being accordingly both operated to the inner position thereof and the rod I I3 being moved to the right with a force corresponding to the braking effect. on either of the axles I5 and I6.

As may be ascertained by referring to Fig. 8, the.

. the switches I and I95 are opened, due to the simultaneous establishment, through switch groups III and I22 of holding circuits in the following manner. The holding circuit for the application magnet valve device 249 and the release magnet valve device 249 is the same as previously described to the point where the wire I is connected to the switch member common to the switches I24 and I25, and thereafter the clrcult is continuedthrough the switch I24 (now closed), wire as, branch wire as, switch m or":

switch group I2I, wire 591, switch I94 of switch group I22, branchwire 599 and wire .454 to ground.

Similarly. the application magnet valve device 249a and the release magnetvalve device 249a are maintained energized despite the-opening of the previously traced circuit at the switch I95, through a holding circuit extending to the point where wire la is connected to the switch member common to the switches I94 and I as previously described, and thereafter through switch I94 (now closed), wire 595, branch wire 599, switch I29 of switchgroup I2I, wire 591, switch I99 of switch group I22',wire 599, and wire 454 e to ground.

It is'possible that the switch groups HI and I 22 may not be operated exactly inunison to the inner position thereof, in which case there may be a momentary interruption of energizing current through the electromagnet coils' of the magnet valve devices 248, 249a, 249 and 249a but due to electrical and magnetic lag the valves are not shifted measurably from the position they occupy\ when the magnet valve devices. are energized. For all practical purposes, it may therefore be said that when the switch groups I2I and I22 are operated from the central or neutral position thereof to the inner position thereof as lust described, the magnet valve devices 249, 248a, 249

' and 249a reman energized with a consequent maintenance of he excitation ofthe eddy current brake coils 92 and 62a oi'the brake devices 21 and 28 respectively.

As previously stated, movement of the operatingrod 3 of the device 94 to the right is e1.- fected simultaneously with the operation of' theswitch groups I2I and I22 to the inner position thereof. The weighing beam I19 of the load measuring device 94 is accordingly rocked on the fulcrum roller I99 in a counterclockwise direc-.- tion to move the rack rod I99 upwardly against the force of the spring I99 in proportion tc'the degree of braking eflect produced on the axles I5"and is. It will be understood thatthe force with which the rack rod I99 is moved upwardly is dependent upon the position .of the fulcrum roller I99 which is in turn dependent upon the loadacting on the wheel-truck. f

The segment drum I99 of. the'controller I94 is accordingly rotated to a degree determined by the extent of movement of the rack rod I99, the direction of rotation of the segment drum- O01? responding to an upward movement of the com,

tact segments4i9 and 4 relative to theiixed contact members, associated therewith, shownin Fig. 6. As the braking effect on the axles I5 and I6 is increased, due to the increase in the ergized train wires 224, 225 and 2 25.

eration of the brake switch 229.

exciting current supplied to the eddy current brake coils 52 and 92a of the brake devices 21 and 29 respectively, the contact segment III is moved correspondingly until it-disengages all of the fixed contact members 4 I 5, 4 I 5 and 4", which it will be remembered are connected to the en- The circuits previously described, whereby the application magnet, valve devices 249 and 2494 are energized, are accordingly interrupted and theiurther supply of fluid under pressure from the main reservoir Hi to the local reservoirs 252 and 252a is thus cut 01!. There being now no per square inch, it being understood, however,

that the pressure in the local reservoir associated with each individual wheel-truck may vary dependent upon the load on the wheel-truck, the local reservoir pressure being higher for the more heavily loaded wheel-truck and lower for the wheel-truck loaded to a lesser extent.

If for any reason, as for example a rise in the supply voltage for the eddy current brake coils 62'and 52a, the braking effect on the axles I5 and I6- is further increased from that described, the corresponding further rotational movement of the segment drum I93 of the controller I94 wlllcause the contact segment 4I4 to disengage "the fixed contact member associated therewith which is connected to the last energized train wire which'contact member, for the degree of braking selected by brake switch 229, and in the operation assumed this happens 'to be the .furtherincrease in the pressure of the fluid actcontact member 433 connected to train wire 229.

The circuits for energizing the release magnet valve devices 249 and 249a are thus interrupted and the pressure of the fluid in the local volume reservoirs 252 and 252a relieved by venting of fluid under pressure from the pipes 219 and 219a to atmosphere under the control of the release magnet valve devices 249 and 249a. With such decrease in local reservoir pressure, the pressure with which the piston 924 presses together the carbon blocks 3I9 offtherheostat devices 254 a and 254ais relieved and the resistance of the rheostat devices is acccrdingly'increased to effect a decrease in-the exciting current for the eddy current brake coils'62 and 62a. The fluid pres-' sure in the local reservoirs 252 and 252a will be reduced until the braking effect produced on the axles I5 and I5 is' lowered sufficiently by the reduction in the exciting current of the eddy current brake coils 52, and 6211 that the contact segment 4 is moved backlaga in into contact with the fixed contact member 433, at which time the holding circuits, previously described, for

energizing the release magnet valve devices 249 and 2 9a are again established and further reduction in the fluid pressure in thelocal reser; voirs 252 and252a is accordingly cut on.

It will thus be seen that the ultimate degree of adhesion utilization or' of braking effect effective on all wheels of all wheel-trucks is uniform and is limited to the degree selected by op- As is well known, the braking efi'ect produced on the axles i5 and I3 by the eddy current brake portion of the brake devices 2? and 28, respectively, while fairly constant over a wide range of speeds will diminish inherently as the speed of rotation of the axle and the motor armature shaft reduces below some relatively low value. Thus the torque forces applied to the followers 99 and 99a of the device 33 through the medium of the torque rods 32 and 89a (see 1) automatically decrease in value with the result that the torque spring 63 causes outward movement of the follower members 89 and 89a. The roller HI, engaging the head M2 on the actuating rod H3, is thus moved to the left as viewed in Fig. 1, and the spring i963 of the load measuring device 39 accordingly becomes effective to shift the rack rod m3 downwardly to cause reverse rotation of the segment drum 593 of the controller E99 to' such an extent that the contact segment M3 reengages the last fixed contact member which is connected to one of the energized train wires 22 i, 225 and 223, which in the case assumed happens to be the contact member 9H, and thus reestablishes a circuit for energizing the application magnet valve devices 293 and 293a.

Fluid under pressure is accordingly again supplied from the main reservoir22l to the local reservoirs 252 and 252a under the control of the application magnet valve devices 249 and 298a, respectively, to further build up the fluid pressure in the diaphragm devices 255 and 255a to cause further reduction in the resistance of the rheostat devices 252 and 259a and a corresponding increase in the degree of the exciting current for the eddy current brake coils 62 and 62a. As the degree of the braking effect produced on the axles I5 and I6 by the brake devices 27 and 28 correspondingly increases, the segment drum I93 of the controller i9 3 is again rotated in the manner previously described, until the contact segment M3 disengages the fixed contact members M5, M5 and the contact member lI'I connected to the last energized train wire 226, whereupon the circuits for energiing the application magnet valve devices 298 and 298a are again interrupted and further increase in the degree of the exciting current of the eddy current brake coils 62 and 32a cut off. I

As the speed of rotation of the axles I5 and i6 is further reduced, the above operation is repeated to increase the degree of exciting current for the eddy current brake coils 62 and 6211 until fluid pressure in local reservoirs 252 and 252a attains a predetermined pressure such as forty pounds per square inch when the spring 331 of the pressure limiting devices 253 and 255a is compressed to absorb further increase in pressure acting on the diaphragm devices 255 and 255m and to thereby prevent further increase in the -degree of pressure applied to compress the carbon blocks 3I9 of the rheostat devices 259 and- 254a. The rheostat devices 256 and 259a are thus ineffective to further increase the degree of exciting current supplied to the eddy" current local reservoirs 252 and 252a so that the pressure therein is increased above the predetermined degree, namely forty pounds per square inch, sufficient to effect operation of the relay valve devices 253 and 253a respectively. Movement of the slide valve of the valve devices 253 and 253w to first lap or cover the exhaust port and subsequently to uncover the inlet port is accordingly effected and fluid under pressure is thus supplied from the local reservoirs 252 and 252a to the pressure cylinders 33 of the brake devices 2i and 29, respectively, application of the friction brake thereof being thus efiected.

When the pressure of the fluid in the brake cylinders 39 and thus in the chamber 392 of the valve devices 253 and 2531;, added to the tension of spring 3E3, exceeds the local reservoir pressure, the slide valve 308 is accordingly shifted to lap position, wherein the supply port SM is covered at the same time as is the exhaust port 3H, to hold the pressure in the brake cylinders 38. Since the tension in spring 3I3 balances substantially forty pounds perv square inch of local reservoir pressure, it will be apparent that the pressure in the brake cylinders 38 will always be substantially forty pounds per square inch less in pressure than the pressure in the local reservoirs 252 and 252a.

The friction brake bands 3? of the brake devices 27 and 28 are thus actuated into frictional engagement with the brake drum members 36 of the brake devices to produce ,a braking effect supplemental to that produced by the eddy current brake of the brake devices 21 and 23.

When the combined braking effect produced by the eddy current brake and the friction brake of the brake devices 2'! and 28 produces sufficient movement of the segment drum I93 of the controller I93, the contact segment H3 disengages the fixed contact member till which is connected to the last energized train wire 226 and the circuits for energizing the application magnet valve devices 298 and 293a. are accordingly interrupted to out off the further supply of fluid under pressure from main reservoir 22E to the local reservoirs 252 and 252a.

If, upon the application of the friction brake of the brake devices 21 and 28; the total braking effect produced on the axles I5 and I6 is higher than that just described, further rotation of the segment drum I93 occasioned thereby will cause the contact segment M4 to disengage the flxed contact member 233 connected to the last energized train wire 223 and the release magnet valve devices 299 and 269a will accordingly be deenergized to effect relief of the pressure of the fluid in the local reservoirs 252 and 252a. Spring 3I3 in the relay device 253 accordingly becomes efiective toshift the slide valve 303 to the left to uncover the exhaust port 3I5. Fluid under pressure is accordingly released from the brake cylinders 38 of the brake devices 21 and 28 until the total braking effect produced by the eddy current and friction brakes of the brake devices 27 and 28 for the axles I5 and I6, respectively, is insufficient to maintain the segment drum I93 of the controller I94 in such position that the contact segment 4 disengages the contact member 933. Rte-engagement of the contact member AM of controller I94 with the contact member 433 reestablishes the circuits for energizing the release magnet valve devices 249 and 249a and thus further release of fluid under pressure from the local reservoirs 252 and 252a is cut off. When the pressure in the pressure cylinders 38 of the brake de- 451 of the magnet vices21 and 23 is reduced sumciently, the fluid pressure acting in the piston chamber of the relay devices 233 and 233a becomes effective to again shift the slide valve tothe right-to lap or cover the exhaust passage and cut oil. further reduction in the pressure of, the ders 33. It will thus again be observed that the relay devices 233 and 233:; so control the'pressure of the fluid supplied to thepressure cylinders 33 that the fluid pressure in the pressure cylinders 331s always a substantially fixed amount (for example, forty pounds per square inch) less than the pressure of the fluid in the local reservoirs 232 and 232a. t

As the speed of the vehicle or train-of cars further diminishes and the braking effect of 'the eddy current brake of the brake devices 21 and 23 on the .axles I 3 and I3 is accordingly reduced substantially to zero; the controller I34 functions,

in the manner previously described, to cause'further build up in the fluid pressure of local reservoirs 232 and 23211 and the consequent operation of the relay valve devices 253 and 233a to further build up the pressure of the fluid in the pressure cylinders 33 of the brake devices 21 and 23. Whenthe vehicle or train of cars is finally brought to a stop the pressure of the fluid in the pressure cylinders 33 is such as to apply'the brake band, 31 without sliding the wheels-on the axles-l3 and I3 and without shock or discomfort to passengers.

It will thus be understood that all the operating mechanisms 3 I, one for each individual wheel-. truck, function simultaneously, in the manner described, to separately regulate the degree of adhesion utilization or of braking effect produced on the axles of each wheel-truck correspondingto axles I5 and I6 shown in Fig. 1, in accordance with the degree selected by the brake switch 223. Upon the stopping of the vehicle or train of cars, the vibration'relay 23I becomes effective to cause energization of the coil 414 of the relay 234 and the. connection from the positive terminal of the battery 235 to the train wire 233 established by the relay 234 is thus interrupted. The circuits for energizing the relays 231 and 25111 controlling the eddy current brake coils 32 and 32a, respectively, as well as the circuits for energizing the magnet valve devices 233 associated with the load measuring devices 34 are thus interrupted. Deene'rgization of the relays-251' and 231a for each wheel-truckaccordingly interrupts the circuit connection .of the eddy current brake coils and 62a to the train wire 233 and excitation of the eddy current brake coils 32 and 32a is accordingly cut off in order to prevent consumption of power needlessly while cars is stopped.

Upon the deenergization' of the 'electrornagnet valve devices 233, the spring 466 becomes effective to shift the valves 433 and 459 so that fluid under pressure is supplied'from the main reservoir pipe 222 to the. piston chamber I11 and piston cylinder. I of the load measuring device 34, throughbranch pipe 2I I-, chamber 464, past the valve 433, chamber 432, and pipe the vehicle or train of and passage 2I2. The bell crank I31 (Figi2) is.

accordingly actuated in a clockwise direction, in the manner previously described, until the roller IGI engages the contact surface I32 on the truck frame. Thus, if the total load on the wheel-truck changes due to load taken on or discharged from the vehicle or car, the position of the fulcrum roller I33 is adjusted, in the manner previously described, sothat upon subsequent application of fluid in the pressure cylin- -243,pipe

15 the brakes the degree of braking effect on the .axles of the wheel-truck will be in accordance with the load on the wheel-truck.

Y It will be understood that in theevent that the current supply to the eddy current brake coils 32 and 32a fails, for some reason, the pressure in the local reservoirs 232 and 232a will be automatically built up to cause application of the friction and 23. the controlbrake of the brake devices 21 ler I34 functioning as described above to regulate the degree of the braking eflect in accordance with the degree selected by operation of the brake switch device 223.

Ormrron (D) Minor inequality of braking effects on diljerent wheels It will be recalled that in the operation of the equipment previously described it was assumed that the braking effect produced on the two axles I3 and I3 was substantially equal at all times. If, however, the braking effect produced on one axle, for example the axle I3, is greater than on' force urging the rod 34 of the device 33 inwardly will be greater than that urging the rod 34:: inwardly and consequently, if the diiference in the braking eifect on the two axles is between the two predetermined amounts above mentioned, then the follower 33 will remain in the inner position with the switch group I2I correspondingly positioned in its inner position, whereas the follower 33a will be moved to its central or neutral position as shown in Fig. 1 and in which the switch group I22 is correspondingly positioned in its central or neutral position. The circuit for energizing magnet valve devices 243 and 243 with both of the switch groups HI and I22 in the inner position thereof, it will be recalled, extends in series through the switches 123, I24 and I23 of'the switch group I2I as well as through switch I33 of the switch group i22, and thus when the switch group I22 is shifted from its inner position to-its central position, as Just described, the circuit for energizing the magnet valve devices 243 and 243 is interrupted due to the opening of.

the switch I33 of the switch group I22. (See Figs.

7 and 8.)

0n the'other hand, as will be recalled, with switch group I22 in its central position as in Fig.

7, the circuit for energizing the magnet valve devices 243a and 243a extends in series through the switches I33 and I33 01 the switch group I22 independently of any of the switches in the switch group I2I, and thus the magnet valve devices 243a and-249a are maintained energized.

It will thus be understood that due to the deenergization of the magnet valve devices 243 and 213 leading to the local reservoir 232 is cut off from the main reservoir pipe 222 and connected to atmosphere to relieve the pressure in local reservoir 232, whereas the pipe 213a leading to local reservoir 232a continues to have fluid under pressure supplied thereinto from the 

